System and method for reducing fuel consumption of a work vehicle based on estimated parastic power losses

ABSTRACT

In one aspect, a system and method allow for various pairs of candidate gear ratios and engine speeds to be identified for achieving a desired ground speed of a work vehicle. The individual operating efficiencies of one or more of the power-consuming components of the work vehicle may then be analyzed for each pair of transmission/engine settings to estimate the associated parasitic power loss(es) within the system. Based on the parasitic power loss value determined for each transmission/engine setting, a net engine power or torque requirement can be calculated and used as an input for determining the fuel efficiency of the work vehicle at each candidate setting. The gear ratio and corresponding engine speed of the candidate setting associated with the lowest fuel consumption may then be set as the target or desired transmission/engine setting for maintaining the work vehicle at the desired ground speed.

FIELD OF THE INVENTION

The present subject matter relates generally to systems and methods forreducing the fuel consumption of work vehicles and, more particularly,to a system and method for reducing the fuel consumption of a workvehicle based on estimated parasitic power losses of one or morepower-consuming components of the work vehicle while the vehicle isoperating within an automatic efficiency or cruise control mode.

BACKGROUND OF THE INVENTION

Current work vehicles, such as tractors and other agricultural vehicles,include an electronically controlled engine and a transmission, such asa power shift transmission (PST) or a continuously variable transmission(CVT). In many instances, an operator may request that the engine andtransmission of a work vehicle be automatically controlled via anassociated vehicle controller to maintain the work vehicle at a givenground speed. In such instances, it is desirable to select theoperational settings for the work vehicle in a manner that maximizes thevehicle's fuel efficiency. However, while the efficiency characteristicsof conventional engines are relatively straight forward, theefficiencies of other power-consuming components of a work vehicle aretypically complex and highly dynamic in nature. Thus, selecting theoptimal operational settings in order to achieve the desiredproductivity while minimizing fuel consumption can be quite challenging.

In current control systems, algorithms have been developed that focussolely on the engine speed control strategy. For example, engine speedis typically controlled based on the vehicle loads, with the enginerunning at its most efficient settings when loads are relatively low.Unfortunately, such control algorithms fail to take into account therole that other power-consuming components play in impacting the overallefficiency of the vehicle.

Accordingly, a system and method for reducing the fuel consumption of awork vehicle based on estimated parasitic power losses of one or morepower-consuming components of the work vehicle while the vehicle isoperating within an automatic efficiency mode would be welcomed in thetechnology.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present subject matter is directed to a method forreducing the fuel consumption of a work vehicle having an engine and atransmission coupled to the engine. The method may generally includereceiving, with one or more computing devices, a speed command signalassociated with a desired ground speed for the work vehicle, andidentifying, with the one or more computing devices, a plurality ofunique candidate transmission/engine settings based on the desiredground speed, wherein each candidate transmission/engine settingincludes a candidate gear ratio and a corresponding candidate enginespeed for achieving the desired ground speed. Additionally, the methodmay include estimating, with the one or more computing devices, a powerloss value associated with operation of the work vehicle at eachcandidate transmission/engine setting, with each power loss valueincluding estimated values of consumed engine power for two or morepower-consuming components of the work vehicle during operation at theassociated candidate transmission/engine setting. The method may alsoinclude determining, with the one or more computing devices, an enginetorque requirement for each candidate transmission/engine setting thatallows the desired ground speed to be achieved based on the power lossvalue associated with such candidate transmission/engine setting, andanalyzing, with the one or more computing devices, stored fuelefficiency data for the work vehicle based on the engine torquerequirement determined for each candidate transmission/engine setting toidentify a target transmission/engine setting of the plurality ofcandidate transmission/engine settings that will minimize fuelconsumption while achieving the desired ground speed. Moreover, themethod may include controlling, with the one or more computing devices,the operation of the work vehicle such that a transmission ratio of thetransmission and an engine speed of the engine correspond to thecandidate gear ratio and the candidate engine speed, respectively, ofthe target transmission/engine setting.

In another aspect, the present subject matter is directed to a systemfor reducing the fuel consumption of a work vehicle. The system mayinclude an engine, a transmission operatively coupled to the engine, anda controller configured to control the operation of the engine and thetransmission. The controller may include a processor and associatedmemory. The memory may store instructions that, when executed by theprocessor, configure the controller to receive a speed command signalassociated with a desired ground speed for the work vehicle, andidentify a plurality of unique candidate transmission/engine settingsbased on the desired ground speed, wherein each candidatetransmission/engine setting includes a candidate gear ratio and acorresponding candidate engine speed for achieving the desired groundspeed. In addition, the controller may be configured to estimate a powerloss value associated with operation of the work vehicle at eachcandidate transmission/engine setting, with each power loss valueincluding estimated values of consumed engine power for two or morepower-consuming components of the work vehicle during operation at theassociated candidate transmission/engine setting. The controller mayalso be configured to determine an engine torque requirement for eachcandidate transmission/engine setting that allows the desired groundspeed to be achieved based on the power loss value associated with suchcandidate transmission/engine setting, and analyze stored fuelefficiency data for the work vehicle based on the engine torquerequirement determined for each candidate transmission/engine setting toidentify a target transmission/engine setting of the plurality ofcandidate transmission/engine settings that will minimize fuelconsumption while achieving the desired ground speed. Moreover, thecontroller may be configured to control the operation of the workvehicle such that a transmission ratio of the transmission and an enginespeed of the engine correspond to the candidate gear ratio and thecandidate engine speed, respectively, of the target transmission/enginesetting.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a side view of one embodiment of a work vehicle inaccordance with aspects of the present subject matter;

FIG. 2 illustrates a schematic view of one embodiment of a system forreducing the fuel consumption of a work vehicle in accordance withaspects of the present subject matter;

FIG. 3 illustrates a flow diagram of one embodiment of a method forreducing the fuel consumption of a work vehicle in accordance withaspects of the present subject matter;

FIG. 4 illustrates a chart providing example efficiency data for thefuel consumption of an engine of a work vehicle in accordance withaspects of the present subject matter;

FIG. 5 illustrates a graph providing example efficiency data for thepower consumption of a hydrostatic unit of a continuously variabletransmission of a work vehicle in accordance with aspects of the presentsubject matter;

FIG. 6 illustrates a graph providing example efficiency data for thepower consumption of a planetary unit of a continuously variabletransmission of a work vehicle in accordance with aspects of the presentsubject matter;

FIG. 7 illustrates a graph providing example efficiency data for thepower consumption of a fan of a work vehicle in accordance with aspectsof the present subject matter;

FIG. 8 illustrates a graph providing an example slip heat limit curvefor a fan of a work vehicle in accordance with aspects of the presentsubject matter;

FIG. 9 illustrates a graph providing example efficiency data for analternator of a work vehicle in accordance with aspects of the presentsubject matter;

FIG. 10 illustrates a graph providing example efficiency data for thepower consumption of a power take-off of a work vehicle in accordancewith aspects of the present subject matter;

FIG. 11 illustrates a graph providing example efficiency data for thepower consumption of a drive axle assembly of a work vehicle inaccordance with aspects of the present subject matter; and

FIG. 12 illustrates a flow diagram of another embodiment of a method forreducing the fuel consumption of a work vehicle in accordance withaspects of the present subject matter.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

In general, the present subject matter is directed to a system andmethod for reducing the fuel consumption of a work vehicle.Specifically, the disclosed system and method may be utilized tominimize fuel consumption while maintaining the desired performance andproductivity of the work vehicle. For example, in several embodiments, acontroller of the work vehicle may receive a speed command input fromthe vehicle operator associated with a desired ground speed for the workvehicle. The controller may then identify suitable operating settingsfor the vehicle's transmission and engine based on the desired groundspeed. For instance, a plurality of unique candidate transmission/enginesettings may be identified by the controller, with eachtransmission/engine setting corresponding to a pair of operationalsettings including a candidate gear ratio for the transmission and acorresponding candidate engine speed for the engine that can be used toachieve the desired ground speed. Upon identification of the variouscandidate transmission/engine settings for achieving the desired speed,the controller may be configured to estimate a parasitic power lossvalue for each candidate setting that is associated with the consumedengine power of one or more power-consuming components of the workvehicle. For example, in one embodiment, the controller may estimate aparasitic power loss associated with each candidate transmission/enginesetting that takes into account engine-related power losses,transmission-related power losses, fan power losses, alternator powerlosses, tire-related power losses, power take-off losses, and/or anyother parasitic power losses associated with any power-consumingsubsystems of the work vehicle. The estimated parasitic power loss valuefor each candidate setting may then be used to calculate the associatedengine torque requirement for achieving the desired ground speed, whichmay then be used to determine which of the identified candidate settingsresults in the lowest fuel consumption while still allowing the desiredground speed to be maintained constant. The gear ratio and engine speedassociated with the candidate transmission/engine setting having thelowest fuel consumption may then be set as the target gear ratio andengine speed for the work vehicle.

It should be appreciated that, in several embodiments of the presentsubject matter, the disclosed system and method may be implemented whenthe work vehicle is operating in an auto-efficiency or cruise controlmode. For example, as indicated above, the operator may request that thework vehicle be maintained at a given ground speed. In such instance,the controller may be configured to control the operation of thevehicle's engine and/or transmission so as to maintain the work vehicleat the requested speed. In doing so, the present subject matter may beutilized to allow a gear ratio and associated engine speed to beselected by the controller that minimizes fuel consumption duringoperation within such auto-efficiency mode.

As will be described below, in several embodiments, the parasitic powerloss value determined for each candidate transmission/engine setting maytake into account the individual power loss values of any number ofpower-consuming components of a work vehicle. For instance, in oneembodiment, the parasitic power loss value determined for each candidatetransmission/engine setting may take into account the individual powerloss values of each power-consuming component of the work vehicle.Alternatively, the parasitic power loss value determined for eachcandidate transmission/engine setting may only take into account theindividual power loss value of a single power-consuming component of thework vehicle or the individual power loss values of a sub-set of thepower-consuming components of the work vehicle. For example, in oneembodiment, the parasitic power loss value for each candidatetransmission/engine setting may be determined as a function of thefan-based power losses and/or the alternator-based power losses for thework vehicle.

Referring now to the drawings, FIG. 1 illustrates a side view of oneembodiment of a work vehicle 10. As shown, the work vehicle 10 isconfigured as an agricultural tractor. However, in other embodiments,the work vehicle 10 may be configured as any other suitable work vehicleknown in the art, such as various other agricultural vehicles,earth-moving vehicles, loaders and/or various other off-road vehicles.

As shown in FIG. 1, the work vehicle 10 includes a pair of front wheelsand associated tires 12, a pair or rear wheels and associated tires 14,and a chassis 16 coupled to and supported by the wheels/tires 12, 14. Anoperator's cab 18 may be supported by a portion of the chassis 16 andmay house various input devices, such as a control lever 20 and/or afoot pedal 21, for permitting an operator to control the operation ofthe work vehicle 10. As will be described below, one or more of theinput devices may be used to allow the operator to provide a speedcommand to an associated controller of the work vehicle 10 thatindicates a desired ground speed for the vehicle 10. Additionally, thework vehicle 10 may include an engine 22 and a transmission 24 mountedon the chassis 16. The transmission 24 may be operably coupled to theengine 22 and may provide variably adjustable gear ratios fortransferring engine power to the wheels via a drive axle assembly 26.The engine 22, transmission 24, and drive axle assembly 26 maycollectively define a drive train 28 of the work vehicle 10.

It should be appreciated that the configuration of the work vehicle 10described above and shown in FIG. 1 is provided only to place thepresent subject matter in an exemplary field of use. Thus, it should beappreciated that the present subject matter may be readily adaptable toany manner of work vehicle configuration. For example, in an alternativeembodiment, a separate frame or chassis may be provided to which theengine 22, transmission 24, and drive axle assembly 26 are coupled, aconfiguration common in smaller tractors. Still other configurations mayuse an articulated chassis to steer the work vehicle 10, or rely ontracks in lieu of the wheels/tires 12, 14. Additionally, although notshown, the work vehicle 10 may also be configured to be operably coupledto any suitable type of work implement, such as a trailer, spray boom,manure tank, feed grinder, plow, seeder, planter, tillage implement,and/or the like.

Referring now to FIG. 2, a schematic diagram of one embodiment of asystem 100 for reducing the fuel consumption of a work vehicle 10 isillustrated in accordance with aspects of the present subject matter. Asshown, the system 100 may include various drive train components of thework vehicle 10, such as the engine 22, the transmission 24 and thedrive axle assembly 26. As is generally understood, the drive axleassembly 26 may include a differential 102 coupled to an output shaft104 of the transmission 22 and one or more axle shafts 106 coupled tothe differential 102 for transferring power to the drive wheels of thevehicle 10 (e.g., the rear wheels).

Additionally, the system 100 may include various other power-consumingcomponents of the work vehicle 10. For example, as shown in FIG. 2, thesystem 100 may include an alternator 108 coupled to an output shaft(s)110 of the engine 22 (shown schematically in FIG. 2 via the associatedarrow) for generating an electrical power output used to power one ormore components of the work vehicle 10. Moreover, as shown in FIG. 2,the system 100 may include a fan 112 coupled to the output shaft(s) 110of the engine 22 (shown schematically in FIG. 2 via the associatedarrow) for generating an airflow through a cooling system (not shown) ofthe work vehicle 10. In one embodiment, the fan 112 may correspond to avistronic fan that utilizes a viscous clutch 114 to control the fanspeed 112. For instance, an associated control valve (not shown) may beelectronically controlled to regulate the supply of fluid to the viscousclutch 114, thereby modulating the degree of engagement of the clutch114 so as to increase or decrease the resulting fan speed. For example,a maximum fan speed may be achieved when the clutch 114 is fullyengaged, with lower fan speeds being achieved by controlling the amountof slip across the clutch 114.

Further, as shown in FIG. 2, the system 100 may also include one or morepower take-offs (PTOs) 116, 118 configured to transfer power from theengine 22 to one or more implements via an associated PTO shaft(s) 120.For instance, in one embodiment, the system 100 may include a front PTO116 configured to be selectively coupled to the output shaft(s) 110 ofthe engine 22 (shown schematically in FIG. 2 by the arrow) via anassociated PTO clutch 122. Additionally, in one embodiment, the system100 may also include a rear PTO 118 configured to be selectively coupledto the engine 22 via an associated PTO clutch 124. In such embodiments,when each PTO clutch 122, 124 is disengaged, the PTOs 116, 118 will notconsume any mechanical power from the engine 22. However, by engagingone or both of the clutches 122, 124, power from the engine 22 may betransmitted through the PTO(s) 116, 118 to the associated shaft(s) 120for rotationally driving an implement(s) coupled thereto.

As will be described below, the various drive train components and otherpower-consuming components of the work vehicle 10 may generally operateat different efficiencies, with each component consuming varying amountsof power at differing vehicle operating parameters. As such, the mostefficient operating conditions for one component may result in decreasedefficiency for one or more other vehicle components. For example, theefficiency of the transmission 24 may be relatively low when the enginesettings (i.e., engine speed and engine torque) are selected to providethe most fuel efficient engine operation. Thus, in accordance withaspects of the present subject matter, the disclosed system 100 andmethod 200 (FIG. 3) may be utilized to enhance fuel efficiency andachieve performance/productivity requirements by taking into account theindividual component efficiencies and associated parasitic power lossesassociated with the various power-consuming components of the workvehicle 10.

As shown in FIG. 2, the system 100 may also include a controller 126configured to control the operation of one or more components of thework vehicle 10, such as the engine 22 and the transmission 24. Forexample, the controller 126 may be communicatively coupled to an enginegovernor 128 in order to control and/or monitor the speed and/or torqueoutput of the engine 22. Similarly, the controller 126 may be coupled tovarious components of the transmission 22 (e.g., one or moretransmission clutches, etc.) in order to adjust the gear ratio of thetransmission 24 to control the output speed thereof.

It should be appreciated that the controller 126 may generally compriseany suitable processor-based device or combination of processor-baseddevices known in the art. Thus, in several embodiments, the controller126 may include one or more processor(s) 130 and associated memorydevice(s) 132 configured to perform a variety of computer-implementedfunctions. As used herein, the term “processor” refers not only tointegrated circuits referred to in the art as being included in acomputer, but also refers to a controller, a microcontroller, amicrocomputer, a programmable logic controller (PLC), an applicationspecific integrated circuit, and other programmable circuits.Additionally, the memory device(s) 132 of the controller 126 maygenerally comprise memory element(s) including, but not limited to,computer readable medium (e.g., random access memory (RAM)), computerreadable non-volatile medium (e.g., a flash memory), a floppy disk, acompact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), adigital versatile disc (DVD) and/or other suitable memory elements. Suchmemory device(s) 132 may generally be configured to store suitablecomputer-readable instructions that, when implemented by theprocessor(s) 130, configure the controller 126 to perform variouscomputer-implemented functions, such as the methods 200, 400 describedbelow with reference to FIGS. 3 and 12. In addition, the controller 126may also include various other suitable components, such as acommunications circuit or module, one or more input/output channels, adata/control bus and/or the like.

It should also be appreciated that the controller 126 may correspond toan existing controller of the work vehicle 10 (e.g., an existing engineand/or transmission controller) or the controller 126 may correspond toa separate controller. For instance, in one embodiment, the controller126 may form all or part of a separate plug-in module that may beinstalled within the work vehicle 10 to allow for the disclosed systemand method to be implemented without requiring additional software to beuploaded onto existing control devices of the vehicle 10.

The system 100 may also include one or more input devices 134communicatively coupled to the controller 126 to allow for operatorinputs to be provided to the system 100. For example, in one embodiment,the work vehicle 10 may include an input device(s) 134 configured topermit an operator to input a speed command corresponding to a desiredground speed for the vehicle 10. Upon receipt of the speed command, thecontroller 126 may be configured to control the various components ofthe work vehicle 10 in order to achieve the commanded ground speed. Forexample, the controller 126 may be configured to regulate the enginespeed and/or the gear ratio of the transmission 24 to adjust the speedof work vehicle 10 to the commanded ground speed. Moreover, in oneembodiment, the input device(s) 132 may be utilized by the operator toinstruct the controller 126 to execute an auto-efficiency mode. In suchan embodiment, upon receipt of the commanded ground speed, thecontroller 126 may be configured to regulate the engine speed and/or thetransmission ratio to maintain the desired ground speed as the workvehicle is traversed across a given surface, such as a field or a road.

Additionally, the system 100 may include one or more sensors formonitoring various operating parameters of the work vehicle 10. Forexample, as shown in FIG. 2, the controller 126 may be communicativelycoupled to various sensors, such as a torque sensor 136 and/or a speedsensor 138, mounted on and/or within the engine 22 for monitoring theengine torque loads and/or the engine speed. In one embodiment, thesensor(s) 136, 138 may comprise an internal sensor of the enginegovernor 128. In another embodiment, the sensor(s) 136, 138 may comprisea separate sensor(s) configured to monitor the torque loads and/or thespeed of the engine 22.

Moreover, the system 100 may also include one or more sensors 140 (e.g.,shaft encoders, shaft sensors and/or any other suitable speed sensors)configured to monitor the rotational speeds of the various shafts of thetransmission 24. For example, as shown in FIG. 2, the transmission 24may include a speed sensor 140 mounted to and/or within the transmissioninput shaft 142 and/or the transmission output shaft 104 to measure theinput and/or output speeds of the transmission 24. The speed sensors 140may, in turn, be communicatively coupled to the controller 126 to permitthe speed measurements to be transmitted to the controller 126 forsubsequent processing and/or analysis. A temperature sensor 144 may alsobe provided to monitor the temperature of the hydraulic fluid beingsupplied to the transmission 24.

In addition, the system 100 may include various other sensors configuredto monitor any other suitable operating parameters of the work vehicle10. For example, in one embodiment, a sensor 146 may be associated withthe drive axle assembly 26 for monitoring one or more operatingparameters of the assembly 26, such as a torque load transmitted throughthe assembly 26, a rotational speed of one or more components of theassembly 26 and/or an axle temperature associated with the assembly 26.Moreover, the work vehicle 10 may include a vehicle speed sensor 148(e.g., a GPS-based device) for monitoring the ground speed of thevehicle 10 and an inclination sensor 150 (e.g., an accelerometer)providing an indication of the slope or inclination of the surfaceacross which the work vehicle is being traversed. Further, the workvehicle 10 may also include a sensor 152 for monitoring one or moreoperating parameters of the alternator 108, such as the alternatorcurrent and/or voltage, as well as a sensor 154 for monitoring one ormore operating parameters of the fan 112, such as the fluid temperaturewithin the fan 112.

As indicated above, the controller 126 may, in several embodiments, beconfigured to execute an auto-efficiency mode corresponding to acontinuous wheel speed operational mode for the work vehicle 10.Specifically, the operator may be allowed to provide an input (e.g., viathe input device(s) 134) requesting that the controller 126 enter theauto-efficiency mode. In doing so, the operator may be requested toinput a desired ground speed for the work vehicle 10. In addition, theoperator may also be requested to input a desired engine speed rangeduring operation within the auto-efficiency mode, such as by requestingthat the operator input maximum and minimum engine speed values for thedesired range. Based on the desired ground speed requested by theoperator, the controller 126 may be configured to calculate theassociated transmission output speed for achieving the desired groundspeed using the final drive gear ratio and the tire radius of the workvehicle 10. The controller 126 may then determine the requested enginespeed using the following control low (Equation 1):

$\begin{matrix}{n_{re} = \frac{n_{do}}{G_{r}}} & (1)\end{matrix}$

wherein, n_(re) corresponds to the requested engine speed, n_(do)corresponds to the desired transmission output speed for achieving thecommanded ground speed, and G_(r) corresponds to the gear ratio of thetransmission.

In one embodiment, when executing the control law of Equation 1, thecontroller 126 may be configured to use the current gear ratio of thetransmission 24 (i.e., the gear ratio at the time the request isreceived to enter into the auto-efficiency mode) to initially calculatethe requested engine speed. Upon calculation of the requested enginespeed, the controller 126 may determine whether the requested enginespeed falls within the engine speed range set by the operator. If thecalculated engine speed for the current gear ratio falls within thedesired engine speed range, the controller 126 may control the operationof the engine 22 to output the requested engine speed in order toinitially achieve the desired ground speed requested by the operator.However, if the calculated engine speed for the current gear ratio fallsoutside the desired engine speed range, the controller 126 may beconfigured to select the closest gear ratio to the current gear ratiothat is associated with a corresponding engine speed that falls withinthe desired engine speed range. For example, if the calculated enginespeed for the current gear ratio is greater than the maximum enginespeed set by the operator, the controller 126 may be configured toincrease the gear ratio and reduce the engine speed (e.g., shiftup-throttle back) until the engine speed calculated via Equation 1 isless than the maximum threshold. Similarly, if the calculated enginespeed for the current gear ratio is less than the minimum engine speedset by the operator, the controller 126 may be configured to reduce thegear ratio and increase the engine speed (e.g., shift down-throttle up)until the engine speed calculated by Equation 1 is greater than theminimum threshold.

As will be described in greater detail below, upon identifying aninitial gear ratio and associated engine speed for achieving the desiredground speed (e.g., the current gear ratio or the closest gear ratiothat satisfies the engine speed limits), the controller 126 may then beconfigured to identify each pair of candidate transmission/engineoperating settings that can potentially achieve the desired groundspeed. For example, given the applicable engine speed limits, thecontroller 126 may identify each combination of a given gear ratio andassociated engine speed that results in the desired ground speed beingachieved. For instance, assuming that the operator requests a desiredground speed corresponding to a transmission output speed of 2000 RPM,the controller 126 may identify multiple candidate ratio/speedcombinations for achieving the desired output speed. An example tableshowing various candidate ratio/speed pairs (e.g., five differentcombinations) that may be available for achieving a transmission outputspeed of 2000 RPM assuming a given transmission configuration isprovided below:

TABLE 1 Example Candidate Transmission/Engine Settings for 2000 RPMOutput Speed Transmission/Engine Setting Pairs Gear Engine SpeedCandidate Ratio/Speed Setting #1 5^(th) 2200 RPM Candidate Ratio/SpeedSetting #2 6^(th) 1900 RPM Candidate Ratio/Speed Setting #3 7^(th) 1650RPM Candidate Ratio/Speed Setting #4 8^(th) 1320 RPM CandidateRatio/Speed Setting #5 9^(th) 1100 RPM

Upon identifying the applicable candidate transmission/engine settings,the controller 126 may be configured to estimate a parasitic power lossvalue for each candidate setting. Specifically, for each gear ratio andassociated engine speed for a given candidate setting, the controller126 may, in several embodiments, estimate an overall parasitic powerloss value associated with operating the work vehicle at the applicablecandidate transmission/engine setting. The overall parasitic power lossfor each candidate setting may then be used to calculate a net enginepower or torque requirement for achieving the desired ground speed atthe associated gear ratio and engine speed, which, in turn, can beanalyzed in light of known fuel efficiency data for the work vehicle 10to identify the specific ratio/speed pair that will minimize fuelconsumption while maintaining operation of the work vehicle 10 at thedesired ground speed.

Referring now to FIG. 3, a flow diagram of one embodiment of a method200 for reducing the fuel consumption of a work vehicle 10 isillustrated in accordance with aspects of the present subject matter.The method 200 will generally be described herein with reference to thework vehicle 10 shown in FIG. 1 and the system 100 shown in FIG. 2.However, it should be appreciated by those of ordinary skill in the artthat the disclosed method 200 may be implemented with any other suitablevehicles having any other suitable vehicle configuration and/or withinany other suitable system having any other suitable systemconfiguration. In addition, although FIG. 3 depicts steps performed in aparticular order for purposes of illustration and discussion, themethods discussed herein are not limited to any particular order orarrangement. One skilled in the art, using the disclosures providedherein, will appreciate that various steps of the methods disclosedherein can be omitted, rearranged, combined, and/or adapted in variousways without deviating from the scope of the present disclosure.

In general, the method 200 may allow for a work vehicle 10 to becontrolled in a manner that minimizes fuel consumption while maintainingthe desired vehicle performance/productivity. Specifically, in severalembodiments, the method 200 may allow for various pairs of candidategear ratios and engine speeds to be identified for achieving a desiredground speed of the work vehicle. The individual operating efficienciesof one or more of the power-consuming components of the work vehicle maythen be analyzed for each pair of transmission/engine settings toestimate the associated parasitic power loss(es) within the system.Based on the parasitic power loss value determined for eachtransmission/engine setting, a net engine power or torque requirementcan be calculated and used as an input for determining the fuelefficiency of the work vehicle at each candidate setting. The gear ratioand corresponding engine speed of the candidate setting associated withthe lowest fuel consumption may then be set as the target or desiredtransmission/engine setting for maintaining the work vehicle at thedesired ground speed.

As shown in FIG. 3, at (202), the method 200 may include receiving aspeed command signal associated with a desired ground speed for the workvehicle. For instance, as indicated above, the work vehicle 10 mayinclude one or more input devices 134 for allowing the operator tocommand or request a desired ground speed. The requested ground speedmay then be transmitted to the controller 126 and used as an input forcontrolling the operation of the transmission 24 and/or the engine 22.

It should be appreciated that, in several embodiments, the controller126 may be configured to receive the speed command signal in connectionwith a request to operate the work vehicle 10 within its auto-efficiencymode. In such embodiments, as indicated above, the controller 126 may beconfigured to initially select the closest gear ratio that allows forthe operator-requested ground speed to be achieved given any applicableengine speed limits, which may correspond to the current gear ratio forthe transmission 24 or may require that the transmission 24 be upshiftedor downshifted in combination with an adjustment in the engine speed.Based on the selected gear ratio and associated engine speed, thecontroller 126 may then control the operation of the engine 22 and/orthe transmission 24, as necessary, to adjust the vehicle's speed to thedesired ground speed. Thereafter, the controller 126 may execute theremainder of the disclosed method 200 to minimize the vehicle's fuelconsumption while ensuring that the work vehicle 10 is maintained at thedesired ground speed.

Referring still to FIG. 3, at (204), the method 200 may includeidentifying a plurality of unique candidate transmission/engine settingsbased on the desired ground speed associated with the received speedcommand signal. Specifically, in several embodiments, each candidatetransmission/engine setting identified by the controller 126 may includea candidate gear ratio and a corresponding candidate engine speed atwhich the desired ground speed may be achieved. Thus, for a given groundspeed, a plurality of different combinations or pairs of gear ratios andassociated engine speeds may be available for selection by thecontroller 126 (e.g., as shown in the example table above).

Additionally, at (206), the method 200 may include estimating aparasitic power loss value associated with operation of the work vehicleat each candidate transmission/engine setting. In one embodiment, theparasitic power loss associated with each candidate transmission/enginesetting may be calculated as a function of the summation of all or aportion of the individual power losses of the various power-consumingcomponents of the work vehicle 10. For instance, Equation 2 provides anexample of various individual power losses that may be utilized todetermine an overall parasitic power loss value for each candidatetransmission/engine setting:

$\begin{matrix}{P_{loss} = {{PL_{engine}} + {PL_{trans}} + {PL_{fan}} + {PL_{alt}} + {PL_{tire}} + {PL_{PTO}} + {PL_{other}}}} & (2)\end{matrix}$

wherein, P_(loss) corresponds to the estimated overall parasitic powerloss for the work vehicle 10 due to system inefficiencies, PL_(engine)corresponds to the power loss associated with operation of the engine 22(e.g., consumed engine friction losses), PL_(trans) corresponds to thepower loss associated with operation of the transmission 24, PL_(fan)corresponds to the power loss associated with operation of the fan 112,PL_(alt) corresponds to the power loss associated with operation of thealternator 108, PL_(tire) corresponds the power loss associated withconsumed tire power, PL_(PTO) corresponds to the power loss associatedwith operation of the PTO(s) 116, 118, and PL_(other) corresponds to thepower loss associated with other power-consuming components of the workvehicle 10, such as the drive axle assembly, the air conditioningcompressor, hydraulic subsystems, etc. The calculation of suchindividual power losses will be described in greater detail below.

It should be appreciated that Equation 2 simply provides one example ofa mathematical formulation that may be used to calculate an associatedparasitic power loss value for each candidate transmission/enginesetting. However, in other embodiments, the parasitic power loss valuefor each candidate transmission/engine setting may be determined as afunction of more or less power loss inputs. For instance, in oneembodiment, the parasitic power loss value for each candidatetransmission/engine setting may be calculated as a function of only asubset of the individual component loss values shown in Equation 2 or asa function of only a single individual component loss value.

It should also be appreciated that the controller 126 is configured tocalculate a separate parasitic power loss value for each candidatetransmission/engine setting. For example, the individual power lossesfor the various power-consuming components may be calculated assumingvehicle operation at the ratio/speed pair associated with each candidatetransmission/engine setting. The individual power losses calculated foreach candidate transmission/engine setting may then be input, forexample, into Equation 2 to determine an overall parasitic power lossvalue for the associated candidate transmission/engine setting.

Moreover, at (208), the method 200 includes determining an engine torquerequirement for each candidate transmission/engine setting that allowsthe desired ground speed to be achieved based on the power loss valueassociated with such candidate transmission/engine setting.Specifically, in several embodiments, the controller 126 may beconfigured to calculate the net engine power available for achieving therequested ground speed at each candidate transmission/engine setting asa function of the parasitic power loss value estimated for suchcandidate transmission/engine setting. As is generally understood, thenet engine power available for satisfying the requested ground speed maygenerally be represented as a function of both the total availableengine power and the associated parasitic power losses. For example, thepower relationship for the work vehicle 10 can be expressed according tothe following equation (Equation 3).

$\begin{matrix}{P_{net} = {P_{engine} - P_{loss}}} & (3)\end{matrix}$

wherein, P_(net) corresponds to the net engine power available tosatisfy the vehicle's current speed requirement, P_(engine) correspondsto the total available engine power, and P_(loss) corresponds to theestimated parasitic power loss for the work vehicle due to systeminefficiencies (e.g., as determined using Equation 2)

By calculating the net engine power available for each candidatetransmission/engine setting, the controller 126 may then determine theassociated engine torque requirement for achieving the desired groundspeed at the ratio/engine pair associated with each candidatetransmission/engine setting. For example, in one embodiment, the enginetorque requirement for each candidate transmission/engine setting may becalculated according to the following equation (Equation 4):

$\begin{matrix}{T_{i} = \frac{P_{{net}{(i)}}*5252}{n_{e{(i)}}}} & (4)\end{matrix}$

wherein, T_(i) corresponds to the torque power requirement (e.g., inft-lbf) for the candidate transmission/engine setting (i), P_(net(i))corresponds to the net engine power (e.g., in HP) estimated for thecandidate transmission/engine setting (i), and n_(e(i)) corresponds tothe candidate engine speed (e.g., in RPM) for candidatetransmission/engine setting (i).

Referring still to FIG. 3, at (210), the method 200 may includeanalyzing stored fuel efficiency data for the work vehicle based on theengine torque requirement determined for each candidatetransmission/engine setting to identify a target transmission/enginesetting of the various candidate transmission/engine settings that willminimize fuel consumption while achieving the desired ground speed.Specifically, using the engine torque requirement determined for eachcandidate transmission/engine setting along with the candidate enginespeed associated with such candidate setting, the controller 126 may beconfigured to determine the most fuel efficient candidate setting forachieving the ground speed requested by the operator.

For example, FIG. 4 illustrates an example of a fuel consumption map foran engine (e.g., engine 22). As is generally understood, the fuel/powerconversion efficiency or brake specific fuel consumption (BSFC) of anengine may vary at different engine settings (i.e., at differentcombinations of engine speed and engine torque). For instance, as shownin FIG. 4, each engine may have an optimal efficiency point 300 at whichthe fuel efficiency of the engine is maximized (i.e. at the minimum BFSCvalue). As such, by using the candidate engine speed for each candidatetransmission/engine setting along with the engine torque requirementcalculated for such candidate setting, a BSFC value may be defined foreach candidate setting. The candidate setting with the lowest BFSC value(and, thus, the lowest fuel consumption) may then be identified as thetarget transmission/engine setting for achieving the desired groundspeed.

It should be appreciated that, in several embodiments, suitable fuelefficiency data (e.g., in the form of fuel consumption maps, datatables, mathematical functions and/or the like) may be stored within thememory 132 of the controller 126 and may be utilized to determine thetarget transmission/engine setting based on the candidate engine speedsand associated torque power requirements for each candidate setting. Forexample, a look-up table may be stored within the controller's memory132 that represents the fuel consumption map for the engine (e.g.,similar to that shown in FIG. 4). In such an embodiment, for eachcandidate engine speed and associated engine torque, the controller 126may reference the look-up table to identify the associated fuelconsumption of each candidate setting.

Referring back to FIG. 3, at (212), the method 200 may includecontrolling the operation of the work vehicle such that a transmissionratio of the transmission and an engine speed of the engine correspondto the candidate gear ratio and the candidate engine speed,respectively, of the target transmission/engine setting. Specifically,upon the identifying the specific candidate transmission/engine settinghaving the lowest fuel consumption value, the controller 126 may beconfigured to control the operation of the engine 22 and thetransmission 24 such that the gear ratio for the transmission 24corresponds to the candidate gear ratio of the target setting and theengine speed corresponds to the candidate engine speed of the targetsetting.

It should be appreciated that the individual component parasitic powerlosses and, thus, the overall parasitic power loss value (P_(loss)) foreach candidate setting may be determined by analyzing specificefficiency data associated with each relevant component of the workvehicle 10. As is generally understood, the efficiency data for eachpower-consuming component may be determined through experimentation,modeling and/or using any other suitable analysis technique and may besubsequently stored within the controller's memory 132. Additionally,the efficiency data, itself, may correspond to transfer functions, othermathematical formulas, tables, charts and/or any other suitable datathat allows the controller 126 to determine the parasitic power lossassociated with each component based on monitored and/or calculatedoperating parameters of the work vehicle 10. In this regard, it is notedthat the efficiency data for a given power-consuming component is oftenavailable from the manufacturer of such component in the form of alook-up table, chart, transfer function, and/or the like.

In general, the various individual parasitic power losses noted abovewith reference to Equation 2 will be described below with reference tomethodologies and/or strategies for determining such parasitic powerlosses based on known data associated with each individualpower-consuming component (e.g., experimentally obtained efficiency dataand/or efficiency data from the component's manufacturer) and/ormonitored or calculated operating parameters of the work vehicle 10.However, given the knowledge of one of ordinary skill in the art withreference to component efficiencies and associated power losses, adetailed description of the calculation and/or determination of suchparasitic power losses will not be provided below for the sake ofbrevity.

Engine Parasitic Power Losses (PL_(engine))

In several embodiments, to determine the parasitic power losses for theengine 22 at each candidate transmission/engine setting, the consumedengine friction losses at each associated candidate gear ratio andengine speed may be estimated as a function of the current load on theengine 22. Typically, such engine friction loss data will be availableas a look-up table or other efficiency/loss data from the manufacturerthat correlates engine friction losses to the engine speed and thecurrent load on the engine 22, with the engine friction losses generallydecreasing with increases in the engine speed. Thus, in one embodiment,the efficiency/loss provided by the engine manufacturer may be storedwithin the controller's memory 132. As a result, by knowing thecandidate engine speed for each candidate transmission/engine setting aswell as by monitoring the current engine load, the controller 126 mayestimate the engine's parasitic power losses for each candidate setting.Alternatively, the parasitic power losses for the engine 22 may bedetermined experimentally, such as by analyzing and compiling test standdata for the engine 22 to develop a mathematical function or look-uptable that correlates engine speed and engine load to the engine'sparasitic power losses.

Transmission Parasitic Power Losses (PL_(trans))

In several embodiments, to determine the parasitic power losses for thetransmission 24 at each candidate transmission/engine setting, thetransmission power losses at each associated candidate gear ratio andengine speed may be estimated as a function of one or more operatingparameters for the transmission 24. For example, such transmission lossdata is typically available as a look-up table or other efficiency/lossdata from the manufacturer that correlates transmission losses to thecurrent gear ratio, transmission input speed, and the temperature of thehydraulic fluid within the transmission 24. Thus, in one embodiment, theefficiency/loss data provided by the transmission manufacturer may bestored within the controller's memory 132. As a result, by knowing thecandidate gear ratio and engine speed for each candidatetransmission/engine setting as well as by monitoring the temperature ofthe hydraulic fluid within the transmission 24, the controller 126 mayestimate the transmission's parasitic power losses for each candidatesetting. Alternatively, the parasitic power losses for the transmission24 may be determined experimentally, such as by analyzing and compilingtest stand data for the transmission 24 to develop a mathematicalfunction or look-up table that correlates the gear ratio, transmissioninput speed, and the temperature of the hydraulic fluid within thetransmission 24 to the associated parasitic power losses.

It should be appreciated that the manner in which the transmission'sparasitic power losses are calculated may vary depending on thetransmission configuration. For example, for a power shift transmission,the majority of the power losses may be associated with losses withinthe transmission's gearbox. In such an embodiment, the parasitic powerlosses may be determined primarily based on the efficiency of thegearbox.

However, for a continuously variable transmission, the power losses maybe associated with the efficiencies of both the hydrostatic drive unitand the planetary gear unit of the transmission. In such an embodiment,the operating efficiency associated with each of the hydrostatic driveunit and the planetary gear unit may be considered to determine theparasitic power losses. For instance, FIGS. 5 and 6 illustrate exampleefficiency data for a continuously variable transmission. Specifically,FIG. 5 provides example efficiency data for a hydrostatic drive unit ofa continuously variable transmission that relates the power consumptionof the hydrostatic drive unit to the engine speed and the pressuredifferential across the pump/motor of the hydrostatic drive unit. Asshown, the power consumption of the hydrostatic drive unit may beinversely related to the engine speed and the pressure differential,with the power consumption generally decreasing with increasing enginespeeds and/or increasing pressure differentials. Similarly, FIG. 6provides example efficiency data for a planetary gear unit of acontinuously variable transmission that relates the power consumption ofthe planetary gear unit to the engine speed (only two example enginespeeds being shown in FIG. 6) and the ground speed of the work vehicle10. As shown, the power consumption of the planetary gear unit may varysignificantly at lower ground speeds and may then steadily increase asthe ground speeds become higher.

Fan Parasitic Power Losses (PL_(fan))

In general, the parasitic power losses for the fan 112 will vary as afunction of the fan speed, with the fan speed, in turn, being dependentprimarily upon the operational parameters of the engine 22, namely theengine speed and engine torque. As indicated above, in severalembodiments, the fan 112 may correspond to a vistronic fan that utilizesa viscous clutch 114 to control the fan speed. In such embodiments, thesupply of fluid to the fan clutch 114 may be regulated to modulate thedegree of engagement of the clutch 114, thereby increasing or decreasingthe resulting fan speed. For example, as indicated above, the maximumfan speed may be achieved when the clutch 114 is fully engaged whilelower fan speeds may be achieved by controlling the amount of slipacross the clutch 114.

In several embodiments, to determine the parasitic power losses for thefan 112 at each candidate transmission/engine setting, an estimated fanspeed may be calculated as a function of both the candidate engine speedand the engine torque requirement associated with such candidatesetting. For example, in one embodiment, a look-up table may be storedwithin the controller's memory 132 that correlates fan speed to thecandidate engine speed and the associated engine torque. As a result, byknowing the candidate engine speed for each candidatetransmission/engine setting as well as by estimating the engine torquerequirement associated with the candidate setting, an estimated fanspeed may be determined by the controller 126. The controller 126 maythen estimate the fan's parasitic power losses for each candidatesetting based on the estimated fan speed. For instance, FIG. 7 providesexample efficiency data for a vistronic fan that relates fan speed tothe associated power losses. As shown, the fan power losses aregenerally a non-linear function of the estimated fan speed, with thepower losses generally increasing with increases in the fan speed.

It should be appreciated that, in one embodiment, the efficiency dataused to determine the fan power losses may derive from the fanmanufacturer. Alternatively, the efficiency data may be determinedexperimentally, such as by analyzing and/or compiling test stand data orany other suitable data that provides an indication of the power lossesof the fan 112 as a function of fan speed.

It should also be appreciated that, as indicated above, the final enginetorque requirement for each candidate transmission/engine setting may becalculated as a function of the candidate engine speed and the netengine power taking into account the various parasitic power losses.Since the parasitic power losses of the fan may, in several embodiments,be considered when calculating the overall parasitic power loss for eachcandidate setting (e.g., per Equation 2), the controller 126 may beconfigured to determine an initial engine torque requirement for eachcandidate transmission/engine setting when estimating the fan speed thatdoes not take into account for fan's parasitic power losses. Forinstance, in one embodiment, the engine torque value used to estimatethe fan speed may correspond to an initial engine torque estimatedetermined as a function of the associated candidate engine speed (e.g.,via a look-up table stored within the controller's memory 132).Alternatively, the overall parasitic power loss may be initiallycalculated without considering fan power losses (e.g., by removing thefan power loss input from Equation 2). This initial parasitic power lossvalue may then be used to calculate the net engine power, which may, inturn, be used to determine an initial engine torque value for estimatingthe fan speed. Once the parasitic power loss for the fan is determinedbased on the estimated fan speed, an updated engine torque value maythen be calculated for the candidate setting that takes into the accountthe fan power losses.

Additionally, it should be appreciated that, while the engine'soperating settings may be used primarily to estimate the fan speed,various other factors may also affect the desired fan speed, including,but not limited to, the fluid temperature supplied to the fan clutch114, the intake manifold temperature, the engine coolant temperature,the refrigerant pressure, and/or the like. In addition, for vistronicfans, the slip heat capacity for the fan clutch 114 may also impact thedesired or achievable fan speed. For instance, FIG. 8 illustrates anexample plot illustrating a slip heat limit curve (indicated by line302) charted as a function of the fan speed and the input speed to thefan 112 (which is directly related to the engine speed). As shown, theslip heat limit curve 302 defines a threshold at which the fan 112 maybe subject to overheating for fan/input speed combinations defined tothe right of the curve 302 (e.g., fan/input speed combinations withinthe cross-hatched area 304). Specifically, operation of the fan 112within the cross-hatched area 304 may be limited to a very short periodof time to prevent overheating. Thus, given the input speed to the fan112, the fan speed must generally be maintained outside thecross-hatched area 304 (e.g., except when the cross-hatched area 304 isbeing briefly traversed to increase the fan speed to a speed definedabove the slip heat limit curve 302).

Alternator Parasitic Power Losses (PL_(alt))

In several embodiments, to determine the parasitic power losses for thealternator 108 at each candidate transmission/engine setting, the powerlosses may be estimated for each candidate engine speed as a function ofone or more operating parameters for the alternator 108. Specifically,the alternator electrical power may generally be determined as afunction of both the current and the voltage for the alternator 108. Forinstance, the alternator electrical power may be expressed according tothe following equation (Equation 5):

$\begin{matrix}{P_{{alt}{(e)}} = {I*V}} & (5)\end{matrix}$

wherein, P_(alt(e)) corresponds to the alternator electrical power, Icorresponds to the alternator current, and V corresponds to thealternator voltage.

Thus, by monitoring the broadcasted or sensed alternator current andvoltage, the controller 1266 may be configured to determine thealternator electrical power, which may then be used to calculate thecorresponding mechanical engine power required to generate suchelectrical power (i.e., the alternator power loss). For instance, in oneembodiment, the parasitic power loss for the alternator 108 may beexpressed according to the following equation (Equation 6):

$\begin{matrix}{{PL}_{alt} = \frac{P_{{alt}{(e)}}}{\eta\left( {\omega,I} \right)}} & (6)\end{matrix}$

wherein, PL_(alt) corresponds to the parasitic power loss for thealternator 108, P_(alt(e)) corresponds to the alternator electricalpower, and η(ω, I) corresponds to the alternator efficiency as afunction of the engine speed and the alternator current.

As noted above, the efficiency of the alternator 108 may generally varyas a function of the engine speed. Thus, for differing candidate enginespeeds, it can be expected that the alternator efficiency will vary. Forexample, FIG. 9 illustrates an example of an alternator efficiency plotas a function of both the alternator current output and the alternatorinput speed (which is directly related to the engine speed). As shown inFIG. 9, the alternator 108 may have an optimal efficiency point 310 atwhich the alternator efficiency is maximized, with bands of decreasedefficiency being defined around the optimal efficiency point 310. Byreferencing such efficiency data, the controller 126 may determine thealternator efficiency as a function of each candidate engine speed andthe associated alternator output current. The alternator power loss maythen be calculated using Equation 6.

It should be appreciated that, in one embodiment, the efficiency dataused to determine the alternator power losses may derive from thealternator manufacturer. Alternatively, the efficiency data may bedetermined experimentally, such as by analyzing and/or compiling teststand data or any other suitable data that provides an indication of thepower losses of the alternator 108 as a function of the engine speed.

Tire-Related Parasitic Power Losses (PL_(tire))

In several embodiments, to determine the tire-related parasitic powerlosses at each candidate transmission/engine setting, the consumed tirepower at each associated candidate gear ratio and engine speed may beestimated as a function of the estimated or measured tire slippage.Specifically, the consumed tire power will generally increase withincreases in the amount of tire slippage. Thus, by estimating ordetecting tire slippage for each candidate setting, the controller 126may estimate the associated tire-related parasitic power losses. In thisregard, experimental data associated with amount of tire slippage may becollected for a plurality of different ratio/speed combinations todevelop a mathematical function or look-up table that correlates tireslippage to various transmission/engine settings. In doing so, theamount of tire slippage may be determined, for example, as a function ofthe differential between the target ground speed for the work vehicle 10and the measured or actual ground speed of the work vehicle 10.Accordingly, when collecting the experimental data, the actual groundspeed of the work vehicle may be monitored and compared to the target orrequested ground speed. The speed differential between the actual andtarget ground speed may then be correlated to the amount of tireslippage.

Power-Take-Off Parasitic Power Losses (PL_(PTO))

In several embodiments, to determine the parasitic power losses for thePTO(s) 116, 118 at each candidate transmission/engine setting, theconsumed PTO power may generally be determined as a function of theengine speed. For example, FIG. 10 provides example efficiency data foreach PTO 116, 118 that relates its power consumption to the enginespeed. As shown, the power consumption of each PTO 116, 118 maygenerally vary linearly with changes in the engine speed. Thus, for eachcandidate engine speed, the controller 126 may determine the associatedparasitic power loss for each PTO 116, 118.

Other Parasitic Power Losses (PL_(other))

It should be appreciated that, in addition to the individual componentsnoted above, the work vehicle 10 may include various otherpower-consuming components that contribute to the total parasitic powerloss for the vehicle 10. For instance, the drive axle assembly 26 of thework vehicle 10 may consume engine power in an amount that varies as afunction of the engine speed. Specifically, FIG. 11 illustrates exampleefficiency data for a drive axle assembly that relates its powerconsumption to both the engine speed and the axle temperature. As shown,the power consumption of the drive axle assembly may generally increasewith increasing engine speeds and/or decreasing axle temperatures.Similarly, other power-consuming components, such as the hydraulicsub-systems, the air conditioning compressor, and/or the like, may alsobe considered when determined the overall parasitic power loss for thework vehicle 10.

Referring now to FIG. 12, a flow diagram of another embodiment of amethod 400 for reducing the fuel consumption of a work vehicle 10 isillustrated in accordance with aspects of the present subject matter.The method 400 will generally be described herein with reference to thework vehicle 10 shown in FIG. 1 and the system 100 shown in FIG. 2.However, it should be appreciated by those of ordinary skill in the artthat the disclosed method 400 may be implemented with any other suitablevehicle having any other suitable vehicle configuration and/or withinany other suitable system having any other suitable systemconfiguration. In addition, although FIG. 12 depicts steps performed ina particular order for purposes of illustration and discussion, themethods discussed herein are not limited to any particular order orarrangement. One skilled in the art, using the disclosures providedherein, will appreciate that various steps of the methods disclosedherein can be omitted, rearranged, combined, and/or adapted in variousways without deviating from the scope of the present disclosure.

As indicated above, when determining the parasitic power loss valueassociated with each candidate transmission/engine setting, theindividual power losses of all or a subset of the variouspower-consuming components may be considered. For instance, the method400 of FIG. 12 will generally be described with reference to using thealternator-based power losses and/or the fan-based power losses, eitheralone or in combination with the parasitic power losses for one or moreof the other power-consuming components, to estimate the overallparasitic power loss value associated with each candidatetransmission/engine setting. Based on the overall parasitic power lossdetermined for each transmission/engine setting, a net engine power ortorque requirement can be calculated and used as an input fordetermining the fuel efficiency of the work vehicle at each candidatesetting. The gear ratio and corresponding engine speed of the candidatesetting associated with the lowest fuel consumption may then be set asthe target or desired transmission/engine setting for maintaining thework vehicle at the desired ground speed.

As shown in FIG. 12, at (402), the method 400 may include receiving aspeed command signal associated with a desired ground speed for the workvehicle. For instance, as indicated above, the work vehicle 10 mayinclude one or more input devices 134 for allowing the operator tocommand or request a desired ground speed. Additionally, in oneembodiment, the controller 126 may be configured to receive the speedcommand signal in connection with a request to operate the work vehicle10 within its auto-efficiency mode. In such an embodiment, thecontroller 126 may be configured to initially select the closest gearratio that allows for the operator-requested ground speed to be achievedgiven any applicable engine speed limits. Based on the initiallyselected gear ratio and associated engine speed, the controller 126 maythen control the operation of the engine 22 and/or the transmission 24,as necessary, to adjust the vehicle's speed to the desired ground speed.Thereafter, the controller 126 may execute the remainder of thedisclosed method 400 to minimize the vehicle's fuel consumption whileensuring that the work vehicle 10 is maintained at the desired groundspeed.

Additionally, at (404), the method 400 may include identifying aplurality of unique candidate transmission/engine settings based on thedesired ground speed associated with the received speed command signal.Specifically, in several embodiments, each candidate transmission/enginesetting identified by the controller 126 may include a candidate gearratio and a corresponding candidate engine speed at which the desiredground speed may be achieved. Thus, for a given ground speed, aplurality of different combinations or pairs of gear ratios andassociated engine speeds may be available for selection by thecontroller 126 (e.g., as shown in the table above).

Moreover, at (406), the method 400 may include estimating at least oneof an alternator power loss value associated with operation of analternator of the work vehicle or a fan power loss value associated withoperation of a fan of the work vehicle for each candidatetransmission/engine setting. For instance, as indicated above, thecontroller 126 may be configured to estimate the alternator-basedparasitic power losses as a function of the candidate engine speedassociated with each candidate setting. Similarly, as indicated above,the controller 126 may be configured to estimate the fan-based parasiticpower losses as a function of both the candidate engine speed associatedwith each candidate setting and an associated estimated torque value forsuch candidate setting.

In one embodiment, the parasitic power loss associated with eachcandidate transmission/engine setting may be determined based solely oneither the alternator-based power losses or the fan-based power losses,or the parasitic power loss may be defined based on the combination orsummation of the alternator-based power losses and the fan-based powerlosses. In another embodiment, the parasitic power loss associated witheach candidate transmission/engine setting may be determined based onthe combination or summation of the alternator-based power losses andone or more individual power losses for one or more otherpower-consuming components (e.g., transmission-based losses, tire-basedlosses, and/or the like). In a further embodiment, the parasitic powerloss associated with each candidate transmission/engine setting may bedetermined based on the combination or summation of the fan-based powerlosses and one or more individual power losses for one or more otherpower-consuming components (e.g., transmission-based losses, tire-basedlosses, and/or the like).

Referring still to FIG. 12, at (408), the method 400 includesdetermining a net engine power for each candidate transmission/enginesetting that allows the desired ground speed to be achieved based atleast in part on the alternator power loss value and/or the fan powerloss value associated with each candidate transmission/engine setting.Specifically, in several embodiments, the controller 126 may beconfigured to calculate the net engine power available for achieving therequested ground speed at each candidate transmission/engine setting asa function of the alternator-based power losses and/or the fan-basedpower losses (e.g., using Equation 3 above). Additionally, as indicatedabove, the individual power losses associated with one or more otherpower-consuming components of the work vehicle may also be consideredwhen determining the net engine power. In such an embodiment, the netengine power for each candidate transmission/engine setting may also bedetermined as a function of such additional power loss values.

Additionally, at (410), the method 400 may include analyzing stored fuelefficiency data for the work vehicle based on the net engine powerdetermined for each candidate transmission/engine setting to identify atarget transmission/engine setting of the various candidatetransmission/engine settings that will minimize fuel consumption whileachieving the desired ground speed. Specifically, in severalembodiments, based on the net engine power, the controller 126 may beconfigured to determine the associated engine torque requirement forachieving the desired ground speed at the ratio/engine pair associatedwith each candidate transmission/engine setting. Thereafter, byreferencing the engine torque requirement determined for each candidatetransmission/engine setting along with the candidate engine speedassociated with such candidate setting, the controller 126 may beconfigured to determine the most fuel efficient candidate setting forachieving the ground speed requested by the operator.

Moreover, at (412), the method 400 may include controlling the operationof the work vehicle such that a transmission ratio of the transmissionand an engine speed of the engine correspond to the candidate gear ratioand the candidate engine speed, respectively, of the targettransmission/engine setting. Specifically, upon the identifying thespecific candidate transmission/engine setting having the lowest fuelconsumption value, the controller 126 may be configured to control theoperation of the engine 22 and the transmission 24 such that the gearratio for the transmission 24 corresponds to the candidate gear ratio ofthe target setting and the engine speed corresponds to the candidateengine speed of the target setting.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for reducing the fuel consumption of a work vehicle having an engine and a transmission coupled to the engine, the method comprising: receiving, with one or more computing devices, a speed command signal associated with a desired ground speed for the work vehicle; identifying, with the one or more computing devices, each unique candidate transmission/engine setting pairs for achieving the desired ground speed, each candidate transmission/engine setting pair including a separate candidate gear ratio and a corresponding candidate engine speed for achieving the desired ground speed at the corresponding candidate gear ratio; estimating, with the one or more computing devices, a power loss value associated with operation of the work vehicle at each candidate transmission/engine setting pair, each power loss value including estimated values of consumed engine power for two or more power-consuming components of the work vehicle during operation at the associated candidate transmission/engine setting pair; determining, with the one or more computing devices, an engine torque requirement for each candidate transmission/engine setting pair that allows the desired ground speed to be achieved based on the power loss value associated with such candidate transmission/engine setting pair; analyzing, with the one or more computing devices, stored fuel efficiency data for the work vehicle based on the engine torque requirement determined for each candidate transmission/engine setting pair to identify a target transmission/engine setting among each of the unique candidate transmission/engine setting pairs that will minimize fuel consumption while achieving the desired ground speed; and controlling, with the one or more computing devices, the operation of the work vehicle such that a transmission ratio of the transmission and an engine speed of the engine correspond to the candidate gear ratio and the candidate engine speed, respectively, of the target transmission/engine setting.
 2. The method of claim 1, wherein receiving the speed command signal comprises receiving the speed command signal in association with a request to execute an operating mode in which a ground speed for the work vehicle is maintained at the desired ground speed.
 3. The method of claim 1, wherein estimating the power loss value comprises: estimating individual parasitic power losses at the associated candidate transmission/engine setting pair for the two or more power-consuming components; summing the individual parasitic power losses together to determine the power loss value.
 4. The method of claim 3, wherein the two or more power-consuming components comprise at least two of the engine, the transmission, a fan, an alternator, a power-take off, a drive axle assembly, or tires of the work vehicle.
 5. The method of claim 3, wherein the two or more power-consuming components comprise the transmission and one of a fan or an alternator of the work vehicle.
 6. The method of claim 3, wherein the two or more power-consuming components comprise tires of the work vehicle and one of a fan or an alternator of the work vehicle.
 7. The method of claim 1, further comprising: upon receipt of the speed command signal, selecting a closest gear ratio at which the desired ground speed can be achieved via operation of the engine at a corresponding engine speed; and controlling the operation of the work vehicle such that an initial transmission ratio of the transmission and an initial engine speed of the engine correspond to the closest gear ratio and the corresponding engine speed, respectively.
 8. The method of claim 7, further comprising receiving an input associated with a requested engine speed range for the engine; wherein selecting the closest gear ratio comprises selecting the closest gear ratio at which the corresponding engine speed falls within the requested engine speed range.
 9. The method of claim 7, wherein controlling the operation of the work vehicle such that the transmission ratio and the engine speed correspond to the candidate gear ratio and the candidate engine speed, respectively, of the target transmission/engine setting comprises adjusting the transmission ratio from the initial transmission ratio to the candidate gear ratio of the target transmission/engine setting and adjusting the engine speed from the initial engine speed to the candidate engine speed of the target transmission/engine setting upon identifying the target transmission/engine setting.
 10. The method of claim 1, further comprising determining a net engine power for each candidate transmission/engine setting pair that allows the desired ground speed to be achieved based on the power loss value associated with such candidate transmission/engine setting pair.
 11. The method of claim 10, wherein determining the engine torque requirement for each candidate transmission/engine setting pair comprises determining the engine torque requirement as a function of the candidate engine speed and the net engine power for each candidate transmission/engine setting pair.
 12. The method of claim 1, wherein analyzing the stored fuel efficiency data for the work vehicle comprises analyzing the stored fuel efficiency data for the work vehicle to identify a fuel consumption value for each candidate transmission/engine setting pair.
 13. The method of claim 12, wherein the target transmission/engine setting is identified as the candidate transmission/engine setting pair having the lowest fuel consumption value.
 14. A system for reducing the fuel consumption of a work vehicle, the system comprising: an engine; a transmission operatively coupled to the engine; and a controller configured to control an operation of the engine and the transmission, the controller including a processor and associated memory, the memory storing instructions that, when executed by the processor, configure the controller to: receive a speed command signal associated with a desired ground speed for the work vehicle; identify each unique candidate transmission/engine setting pair for achieving the desired ground speed, each candidate transmission/engine setting pair including a separate candidate gear ratio and a corresponding candidate engine speed for achieving the desired ground speed at the corresponding candidate gear ratio; estimate a power loss value associated with operation of the work vehicle at each candidate transmission/engine setting pair, each power loss value including estimated values of consumed engine power for two or more power-consuming components of the work vehicle during operation at the associated candidate transmission/engine setting pair; determine an engine torque requirement for each candidate transmission/engine setting pair that allows the desired ground speed to be achieved based on the power loss value associated with such candidate transmission/engine setting pair; analyze stored fuel efficiency data for the work vehicle based on the engine torque requirement determined for each candidate transmission/engine setting pair to identify a target transmission/engine setting among each of the unique candidate transmission/engine setting pairs that will minimize fuel consumption while achieving the desired ground speed; and control the operation of the work vehicle such that a transmission ratio of the transmission and an engine speed of the engine correspond to the candidate gear ratio and the candidate engine speed, respectively, of the target transmission/engine setting.
 15. The system of claim 14, wherein the controller is configured to estimate the power loss value by estimating individual parasitic power losses at the associated candidate transmission/engine setting pair for the two or more power-consuming components and summing the individual parasitic power losses together to determine the power loss value.
 16. The system of claim 14, wherein, upon receipt of the speed command signal, the controller is configured to select a closest gear ratio at which the desired ground speed can be achieved via operation of the engine at a corresponding engine speed, the controller being further configured to control the operation of the work vehicle such that an initial transmission ratio of the transmission and an initial engine speed of the engine correspond to the closest gear ratio and the corresponding engine speed, respectively.
 17. The system of claim 16, wherein the controller is further configured to receive an input associated with a requested engine speed range for the engine, the controller being configured to select the closest gear ratio at which the corresponding engine speed falls within the requested engine speed range.
 18. The system of claim 16, wherein, upon identifying the target transmission/engine setting, the controller is configured to adjust the transmission ratio from the initial transmission ratio to the candidate gear ratio of the target transmission/engine setting and adjust the engine speed from the initial engine speed to the candidate engine speed of the target transmission/engine setting.
 19. The system of claim 14, wherein the controller is further configured to determine a net engine power for each candidate transmission/engine setting pair that allows the desired ground speed to be achieved based on the power loss value associated with such candidate transmission/engine setting pair, the controller being configured to determine the engine torque requirement as a function of the candidate engine speed and the net engine power for each candidate transmission/engine setting pair.
 20. The system of claim 14, wherein the controller is configured to analyze the stored fuel efficiency data for the work vehicle to identify a fuel consumption value for each candidate transmission/engine setting pair. 